Effects of pymetrozine, an antifeedant of Hemiptera, on Asian citrus psyllid, Diaphorina citri, feeding behavior, survival and transmission of Candidatus Liberibacter asiaticus

BACKGROUND: Vector‐borne plant disease management can be enhanced by deployment of antifeedants in addition to the use of broad‐spectrum neurotoxic insecticides. The effects of pymetrozine on Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, feeding behaviour, survival and transmission of Candidatus Liberibacter asiaticus (Las), the presumed causal pathogen of huanglongbing, were investigated. RESULTS: Pymetrozine applied at 52 and 104 µg mL^?1 to citrus plants [Swingle citrumelo (X Citroncirus webberi Ingram and Moore)] modified the feeding behavior of ACP and increased the amount of time spent performing non‐penetration behaviors while decreasing the time spent performing ingestion behaviors compared with the controls 1 day after treatment. However, the antifeedant effect of pymetrozine subsided 5 days after application. Pymetrozine reduced the survival of both adults and nymphs on treated plants compared with the control. However, it had a greater impact on survival of nymphs than on survival of adults. Pymetrozine applied at 52 and 104 µg mL^?1 on Las‐infected ‘Valencia’ sweet orange plants [Citrus sinensis L. (Osbeck)] reduced acquisition (12 and 21% respectively) and transmission (11 and 18% respectively) of Las by feeding ACP adults compared with the controls; however, these reductions were not statistically significant. CONCLUSIONS: Pymetrozine exhibited moderate antifeedant effects by modifying the feeding behavior of ACP adults with short residual activity. The impact of pymetrozine on survival of nymphs was greater than on adults at the higher concentrations tested. Pymetrozine also reduced the acquisition and transmission of Las by feeding ACP adults up to 21 and 18%, respectively, compared with untreated controls. Copyright © 2010 Society of Chemical Industry     

Rapid and sensitive detection of “<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter asiaticus” by cycleave isothermal and chimeric primer-initiated amplification of nucleic acids

We developed a detection method for “Candidatus Liberibacter asiaticus”, causal agent of citrus huanglongbing, using isothermal and chimeric primer-initiated amplification of nucleic acids combined with cycling probe technology (Cycleave ICAN). With Cycleave ICAN, the reaction was done in one tube in 1 h without the need for electrophoresis, and false positives were not generated. In addition, Cycleave ICAN method was more sensitive than the conventional PCR method. Cycleave ICAN helps shorten the time for the large-scale detection needed to manage huanglongbing.     

柑橘木虱的防治技术研究进展

防治柑橘木虱是柑橘黄龙病综合防控的关键措施。本文主要阐述了柑橘木虱的防治技术手段,包括田间管理、化学防治、生物防治等,并且探讨了柑橘木虱防治的发展趋势,旨在为防治柑橘木虱及防控柑橘黄龙病提供理论参考和技术支撑。     

柑桔黄龙病亚洲种病原(Candidatus Liberobacter asiaticus)16S rDNA 的PCR-SSCP分析

应用PCR—SSCP技术对我国柑桔主要产区、泰国和法国留尼湾等地收集到的柑桔黄龙病亚洲种病原（Candidatus Liberobacter asiaticus）16S rDNA进行了分析。PCR结果表明,不同的地区的柑桔黄龙病亚洲种16S rDNA在长度上没有明显区别。进一步的SSCP结果显示,不同地区柑桔黄龙病亚洲种16S rDNA序列在组成上也没有差异。显示来自不同地区、不同寄主品种的柑桔黄龙病亚洲种种内没有存在明显差异。     

Influence of temperature on infection and establishment of ‘Candidatus Liberibacter americanus’ and ‘Candidatus Liberibacter asiaticus’ in citrus plants

The objectives of this work were (i) to determine the influence of temperature on infection of citrus by ‘Candidatus Liberibacter asiaticus’ and ‘Candidatus Liberibacter americanus’, the two bacterial species associated with citrus huanglongbing (HLB) in Brazil, and (ii) to determine the influence of temperature on citrus colonization by ‘Ca. L. asiaticus’, which has taken over from ‘Ca. L. americanus’ as the predominant species in Brazil since 2008. Two experiments were carried out with graft‐inoculated Valencia oranges on Rangpur lime rootstocks. Immediately after inoculation the plants were maintained for 423 days in growth chambers under the following night/day temperature conditions: 17/22, 22/27 or 27/32°C, with a dark/light photoperiod of 8/16 h. Infection and colonization of plants were determined using quantitative PCR (qPCR). ‘Candidatus Liberibacter americanus’ did not infect the plants maintained at 27/32°C; however, infection by ‘Ca. L. asiaticus’ occurred at all studied temperatures. Two months after inoculation, ‘Ca. L. asiaticus’ was distributed throughout the inoculated plants, with mean C_t values in the range of 30–31 for leaves and 25–28 for roots. Over time, ‘Ca. L. asiaticus’ reached the highest titres in mature leaves (mean C_t value = 26·7) of citrus plants maintained at 22/27°C. ‘Candidatus Liberibacter asiaticus’ colonization of citrus plants was negatively affected by the daily temperature regime of 27/32°C (mean C_t value in mature leaves = 33·6).     

三种分子检测体系的比较及柑橘果园黄龙病监测

为了评价3种PCR分子检测体系对柑橘黄龙病(citrus huanglongbing,HLB)大田诊断效果,综合比较了常规PCR、巢式PCR和SYBR Green Ⅰ荧光定量PCR(SG Ⅰ-qPCR)方法对柑橘黄龙病菌检测的灵敏度、特异性和准确度等参数,并用SYBR Green Ⅰ荧光定量PCR和巢式PCR监测广西柑橘园疑似HLB样品425个,比较了2种检测体系的阳性检出率。基于CQULA04F/CQULA04R引物对的SYBR Green Ⅰ荧光定量PCR的灵敏度可达10 ag/μL;而巢式PCR灵敏度为100 ag/μL,巢式PCR较常规PCR检测灵敏度高104倍。疑似样品的HLB病原SYBR Green Ⅰ荧光定量PCR和巢式PCR检出率分别为46.6%、40.0%。各检测体系的灵敏性、特异性、符合度依次为SYBRGreen Ⅰ荧光定量PCR>巢式PCR>常规PCR。研究表明,SYBR Green Ⅰ荧光定量PCR可作为果园大规模HLB早期诊断和监测的首选,而在缺乏定量检测仪器时,巢式PCR也可用于HLB的检测,但需注意避免空气污染导致的假阳性。     

柑橘黄龙病热处理防治技术研究进展

柑橘黄龙病正在中国、巴西和美国等地广泛传播,急需快速、有效的田间防治技术。热水和湿热空气处理对柑橘病苗和嫁接枝条有脱毒作用,在温室环境中对病苗木进行光照热疗,可以减少黄龙病病菌数量,促进其健康生长并有效延长产果寿命。该文针对柑橘黄龙病防治技术的研究现状,综述了基因改良育种、苗木脱毒、化学防治、物理防治和生物防治等方法,结合热疗法在微生物和昆虫杀灭中的广泛应用,分析了田间热处理防治技术研究中存在的主要问题,提出了研究柑橘黄龙病病菌热处理温度阈值和对应时间、建立田间黄龙病病情快速诊断和热处理防治效果评价体系、研究热处理对黄龙病病菌抑制和消杀机理以及不同传热介质在柑橘树体的传热过程和特性、建立黄龙病田间快速热处理系统、研究黄龙病综合防治方法等建议,可为进一步研究柑橘黄龙病田间防治技术提供参考。     

柑桔黄龙病研究的回顾与展望

柑桔黄龙病是由一种叫做韧皮部杆菌(Candidatus Liberibacter)的病原引起的,已经确定的病原有亚洲、非洲和美洲3个种。病害通过种苗、嫁接和木虱介体等途径传播。病害可根据田间症状诊断,也可以通过血清学、电镜技术和PCR等分子生物学等技术进行鉴定。目前,柑桔黄龙病主要依靠综合防治的方法。开展病原的人工培养、抗病育种、致病机理和病害防治方法等方面的研究对揭示病原特性和病害防治等都具有十分重要的意义。     

Rate, placement and timing of aldicarb applications to control Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in oranges

BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a cosmopolitan insect pest of citrus and vectors the bacterium Candidatus Liberibacter asiaticus, a suspected causal organism of citrus greening or ‘huanglongbing’ disease. Aldicarb 150 g kg^?1 GR (Temik^® 15 G) was evaluated at three rates, two placements and three timings for ACP control in orange trees. RESULTS: Application of aldicarb at 5.6, 2.8 and 1.4 kg AI ha^?1 in March 2006 reduced adults by 58–66%, 45–46% and 25–37% respectively compared with untreated controls in two separate trials. No difference was observed in placement (one versus two sides of the tree) or tree size (8 years old versus 12 years old). Application at 5.6 kg ha^?1 in January 2007 reduced adults by 86% and shoot infestation by 77% in spring, and was generally better than the November and especially February applications. Even more striking results were evident on adults caged on treated plants for 25 days in March. Spiders and ladybeetles were equally abundant in treated and untreated trees. CONCLUSION: Aldicarb application at 5.6 kg ha^?1 to the bed side of mature citrus trees 2–3 months before spring growth can suppress ACP through spring without a direct effect on principal psyllid natural enemies. Copyright © 2008 Society of Chemical Industry